120 mercury?

[derekfl]

Looking at a 120 mercury two stroke outboard. Says mid 90s. Says it weighs 310 pounds. And it has a cylinder head. Is this a force motor with mercury, marine written on it? Because the sticker says mercury, marine, Fondulac, Wisconsin. And the force website says 303 pounds. But either way 300 pounds for 120 hp is a decent power to weight ratio for a small boat motor.

[Dave Strong]

4cyl 2+2 motor, good engines.

Dave

[James45157]

sounds like a force as the 4 cyl merc did not have cyl head i had a new one in 1989 worst motor i ever owned they came out in 1988 first few years were not very good if the motor you are looking at has 3 carbs its a force

[ChrisCarsonMarine]

[QUOTE=James45157;3390850]sounds like a force as the 4 cyl merc did not have cyl head i had a new one in 1989 worst motor i ever owned they came out in 1988 first few years were not very good if the motor you are looking at has 3 carbs its a force[/QUOTE
The 3 Carb force is a 5 cylinder 150hp,the 120 has 2 carbs,Chris

[derekfl]

Looks like 2 carb setup. 120 hp. 310 lbs. hard to beat that power/weight ratio without special building a 2.5 v6. Yamaha 90 at 250 lbs may also be option. And probably longer life.

[skialot2]

It's a Force. Mercury never made a 120HP motor. They made 115HP and 125HP in both 4 & 6 cylinder versions. Force produced a 120HP from 1990 thru 1999. 303 lbs. for 120HP is pretty good. (2.525 HP pr lb.) Find an old Merc 1500 inline 6 150HP. At 290 lbs, they are 1.933 HP per lb. Or a 2.4 V6 200. 396 lb. = 1.98 lb. per HP

[derekfl]

it is just the other question: longevity. they did a study with iron inboard engines. the more pounds of weight per horsepower the longer it lasted. when you build a 454 to 450-600 hp, it has a much shorter life then at 330 ho. 75% of weight hp/lb seems to be where iron chebby v8 live longest in a boat. diesels too. you can get mucho more power out of a diesel with bigger injectors and bigger turbo. but it doesn't go as far. i am sure there is a similar correlation with aluminum outboards. part of it is metal mass to survive heat when coolant flow gets low.

[FMP]

103 ci , xflow Merc version of Chrysler piston 95+

[derekfl]

So a merc looper is a better motor, unless weight is a main interest point?

[FMP]

Nothing wrong with them if proper. 165psi , Tbolt or CDM IGN , coated 4 reed swap to CCMS, Merc 2.07:1 case, good tnt, decent on fuel with a good tune.
I'd take it over the L4 Merc.

[derekfl]

picked up a 125 merc with 90 in one hole 120 in the rest. hope i can get away with rings. 200 for the motor. can bet more for either the lower, trim assy or carbs and ignition so not getting hurt. may grab a 100 buck 3 cyl also...